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PubMedDate not supplied

Cross immunological reactions between three haptens of the "para" group and 4-aminoantipyrine.

Cross passive hemagglutination reactions between sulfanilic acid (SA), para-aminobenzoic acid (PABA), p-phenethidine (PT) and 4-aminoantipyrine (4-AA) haptens have been investigated using conjugates of diazo derivaties of these compounds with homologous serum proteins. Intense cross passive hemagglutination reactions were found between PABA, SA and 4-AA haptens. Although anti-PT sera cross reacted intensely with PABA, SA as well as with 4-AA haptens, antibodies cross reacting with PT were not detected in any of the anti-PABA, anti-SA and anti-4-AA antisera. The conjugates containing a heterologous hapten de not substantially alter the titer of the hemagglutination reactions performed with erythrocytes coated with the homologous hapten, but completely suppress the hemagglutination reactions performed with erythrocytes coated with this hapten as well as with other, but not all, heterologous, haptens. The results support the conclusion that the apparent polysensitization to drugs may actually rely upon cross reactions with haptens chemically related to the immunizing one.

4-Aminobenzoic Acid↗
PubMedDate not supplied

Effects of butylated hydroxyanisole and butylated hydroxytoluene on DNA adduct formation and arylamine N-acetyltransferase activity in human bladder tumour cells.

In this study, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) were used to determine the inhibition of arylamine N-acetyltransferase (NAT) activity and DNA adduct formation in human bladder tumour cell line T-24. The activity of NAT was measured by high-performance liquid chromatography, assaying for the amounts of N-acetyl-2-aminofluorene and N-acetyl-p-aminobenzoic acid and remaining 2-aminofluorene and p-aminobenzoic acid. Human bladder tumour cell line T-24 cytosols and intact cells were used for examining NAT activity and carcinogen-DNA adduct formation. The results demonstrated that NAT activity and 2-aminofluorene-DNA adduct formation in human bladder tumour cells were inhibited and decreased by BHA and BHT in a dose-dependent manner. The effects of BHA and BHT on the values of the apparent K(m) and V(max) also were determined in both systems examined. The results indicated that BHA and BHT decreased the apparent values of K(m) and V(max) from human bladder tumour cells in both cytosol and intact cells.

2-Acetylaminofluorene↗
PubMed1995

Quantitation of red blood cell folates by stable isotope dilution gas chromatography-mass spectrometry utilizing a folate internal standard.

We report a new gas chromatography-mass spectrometry (GC-MS) method of measurement of red blood cell folates utilizing a stable isotope-labeled bacterial synthesized folate internal standard. The GC-MS method exploits the fact that the common feature of all folate molecules is a p-aminobenzoic acid moiety sandwiched between a pteridine ring and a polyglutamate chain of varying length. In this method, red blood cell folates together with a folate internal standard are specifically purified using bovine folate binding protein and the folates are subsequently chemically cleaved to p-aminobenzoic acid, pteridines, and glutamic acids. Since all six carbon atoms of the benzene ring in the p-aminobenzoic acid moiety of the folate internal standard are labeled with [13C], it is possible to use selected ion monitoring and stable isotope dilution GC-MS to quantitate folates. The method appears to be sensitive, specific, and accurate. The method has been applied to generate a reference range of red blood cell folates based on assay of 25 normal individuals.

4-Aminobenzoic Acid↗
PubMed2003

Paclitaxel (taxol) inhibits the arylamine N-acetyltransferase activity and gene expression (mRNA NAT1) and 2-aminofluorene-DNA adduct formation in human bladder carcinoma cells (T24 and TSGH 8301).

Acetylator polymorphism in man results from differential expression of human liver N-acetyltransferase. N-Acetyltransferase enzyme activity has been demonstrated to be involved in some types of chemical carcinogenesis. Paclitaxel (taxol) had been shown to affect N-acetyltransferase activity of human lung cancer cells. In this study, paclitaxel was chosen to investigate the effects of arylamine N-acetyltransferase activity (N-acetylation of substrate), gene expression and 2-aminofluorene-DNA adduct formation in human bladder carcinoma cell lines (T24 and TSGH 8301). The N-acetyltransferase activity (N-acetylation of substrates) was determined by high performance liquid chromatography assaying for the amounts of acetylated 2-aminofluorene and p-aminobenzoic acid and nonacetylated 2-aminofluorene and p-aminobenzoic acid. Intact human bladder carcinoma T24 and TSGH 8301 cells were used for examining N-acetyltransferase activity, gene expression and 2-aminofluorene-DNA adduct formation. The results demonstrated that the N-acetyltransferase activity, gene expression (NAT1 mRNA) and 2-aminofluorene-DNA adduct formation in intact human bladder carcinoma cells were inhibited and decreased by paclitaxel in a dose-dependent manner. The effects of paclitaxel on the apparent values of Km and Vmax of N-acetyltransferase enzyme from intact human bladder carcinoma cells were also determined in these cell lines. A marked influence of paclitaxel was observed on the decreasing apparent values of Km and Vmax from intact human bladder carcinoma cells (T24 and TSGH 8301). Thus, paclitaxel is an uncompetitive inhibitor to the NAT enzyme.

4-Aminobenzoic Acid↗
PubMed2001

Arylamine N-acetyltransferase activities in human breast cancer tissues.

N-Acetyltransferase activities were determined in tumor (12 malignant and 6 benign) and control (non-cancerous) breast tissues from 18 female patients. The activities of matched 12 malignant tumor and control tissue cytosols showed 6 rapid, 4 intermediate and 2 slow acetylators based on p-aminobenzoic acid (NAT1) and sulfamethazine (NAT2) as substrates. Compared to the activities of slow acetylators, the rapid acetylators exhibited mean apparent Vmax values about 5- and 50-fold greater for p-aminobenzoic acid and sulfamethazine, respectively. No correlation was observed between the blood and breast tissue N-acetyltransferase (NAT1 and NAT2) activities. When the mean apparent N-acetyltransferase activities of the malignant and benign breast tumor tissues were compared, the results showed an increased activity for both p-aminobenzoic acid (PABA) and sulfamethazine (SMZ) acetylation in the malignant tissues compared to benign ones, and also control tissues showed lower activities compared to tumor tissues. Moreover, the mean NAT2 activity was about 2-fold greater in the malignant tissues when compared to NAT1 activity.

4-Aminobenzoic Acid↗
PubMed1986

Pancreolauryl and NBT-PABA tests. Are serum tests more practicable alternatives to urine tests in the diagnosis of exocrine pancreatic insufficiency?

Serum fluorescein and p-aminobenzoic acid were measured during a urine pancreolauryl and an N-benzoyl-l-tyrosyl-p-aminobenzoic acid (NBT-PABA) test in 22 healthy controls, 17 patients with gastrointestinal nonpancreatic diseases (normal secretin-pancreozymin test), and 31 patients with abnormal exocrine pancreatic function due to chronic pancreatitis. The optimal cutoff point for separating normal from abnormal pancreatic function was after 210 min in the pancreolauryl test and after 150 min in the NBT-PABA test. The latter test was slightly less sensitive and specific than the pancreolauryl test. Serum tests seem to offer a practicable alternative to the established indirect pancreatic function tests in urine and may be used in the elderly and severely ill, as well as in outpatients in whom correct collection of the urine may be difficult.

4-Aminobenzoic Acid↗
PubMed1974

Growth of Pseudomonas C on C1 compounds: continuoous culture.

Pseudomonas C was grown in continuous culture on methanol, formaldehyde, or formate as sole carbon source. On methanol mu(max) = 0.49/h and yield constant (Y) = 0.54; on formaldehyde and on unsupplemented media, mu(max) was about 0.2/h and Y was 0.15, whereas addition of p-aminobenzoic acid, folic acid, serine, or glycine to the medium raised Y to about 0.26 to 0.29, and addition of p-aminobenzoic acid, folic acid, serine, nicotinamide adenine dinucleotide, and Tween 80 raised the yield to 0.35. On formate and on unsupplemented media, mu(max) = 0.2/h and Y = 0.02, whereas addition of 0.1 mM p-aminobenzoic acid increased mu(max) to about 0.47 and Y to about 0.23. At low cell concentrations or growth rates a beneficial effect of CO(2) was observed. Formaldehyde or formate, when added together with methanol, were utilized simultaneously with the methanol.

Aminobenzoates↗
PubMed2000

Stable reversed vesicles in oil: characterization studies and encapsulation of model compounds.

The formation of reversed sucrose ester vesicles in silicon oil and mixtures of silicon oil and isopropyl palmitate was studied. The vesicles were characterized by polarized light microscopy, freeze-fracture electron microscopy, and differential scanning calorimetry. Furthermore the ability to encapsulate p-aminobenzoic acid and cholesterol in such vesicles was studied. The vesicles were multilamellar and had sizes up to several micrometers. The vesicles agglomerated but did not show fusion for at least 2 years when stored at room temperature in glass vials. The encapsulation efficiency of both p-aminobenzoic acid and cholesterol strongly depended on the oil phase in which the vesicles were prepared. Reversed sucrose ester vesicles in silicon oil encapsulated nearly 100% of the amount of p-aminobenzoic acid or cholesterol present in the dispersion. These compounds were encapsulated in different compartments of the vesicles. Reversed sucrose ester vesicles offer new perspectives regarding the development of novel pharmaceutical dosage forms.

4-Aminobenzoic Acid↗
PubMed1976

Rapid incorporation of precursors into candicidin by resting cells of Streptomyces griseus.

Labeled acetate, propionate and p-aminobenzoic acid were efficiently incorporated into candicidin by phosphate-limited resting cells of Streptomyces griseus. The efficiency of incorporation in short-term experiments using phosphate-limited resting cells was similar to that achieved previously in long-term experiments using growing cells. (2-14C)Propionate was more efficiently incorpoated than (1-14C)propionate, (U-14C)propionate, or (U-14C)-acetate. p-Aminobenzoic acid incorporation is linear over a 10-hour period while those of acetate or propionate reach a constant level after approximately 4 hours of incubation. Double-labeled candicidin of high specific activity was prepared by supplementing the resting cell system with (3H)acetate and (14C)p-aminobenzoic acid.

4-Aminobenzoic Acid↗
PubMed1972

Transition of chemolithotroph Ferrobacillus ferrooxidans to obligate organotrophy and metabolic capabilities of glucose-grown cells.

Transition of chemolithotrophic Ferrobacillus ferrooxidans to organotrophy occurred after 60 hr of incubation in an organic medium. Three distinct phases, based on metabolic activities of cells, were observed during the course of transition. Conversion of cellular nutrition to organotrophy resulted in a gradual loss of Fe(2+) oxidation and cessation of CO(2) fixation. These changes were concomitant with a rapid increase in uptake of glucose and phosphate during the latter part of transition period. The outcome of transition was governed by the pH of the medium, temperature of incubation, availability of oxygen, age of the chemolithotrophic cells, and the type of energy and carbon source available to the bacterium. Presence or absence of p-aminobenzoic acid and Fe(2+) ions did not influence transition of cells. A defined medium containing glucose, mineral salts, and p-aminobenzoic acid at pH 2.5 was found to be most suitable for transition and for culture of heterotrophic convertants. Maximum growth rate of the heterotrophic cells was attained with vigorous aeration at 35 C. The bacterium could be cultured on a variety of organic compounds, including complex organic media, provided they were used in low concentrations. Serological studies on autotrophic cells and the heterotrophic convertant have shown a definite antigenic relationship between the two cell types.

Agglutination Tests↗
PubMed1988

Studies on some iridium(III) complexes with Schiff bases derived from amino carboxylic acids.

The reactions of iridium(III) chloride with different Schiff bases gave complexes of types [Ir(SB)3], [Ir(SB')Cl(H2O)2], [Ir(SB'')Cl2]n, [Ir(SB'' ')Cl(H2O)]n (SBH = Schiff bases derived from anthranilic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde or m-hydroxyacetophenone; SB'H2 = Schiff bases derived from anthranilic acid and salicylaldehyde or o-hydroxyacetophenone; SB''H = Schiff bases derived from p-aminobenzoic acid and benzaldehyde, acetophenone, vanillin, cinnamaldehyde, or m-hydroxyacetophenone; SB'' 'H2 = Schiff bases derived from p-aminobenzoic acid and salicylaldehyde or o-hydroxyacetophenone). These complexes have been characterized on the basis of elemental analyses, conductance, magnetic moment, and spectral (electronic, i.r., and 1H n.m.r.) data. The electronic spectra reveals octahedral geometry for these complexes except for [Ir(SB'')Cl2]n, which is trigonal bipyramidal. The thermal behavior of these complexes has also been studied by TG, DTG, and DSC techniques. The different kinetic parameters, viz., order of reaction, activation of energy, and heat of reaction were calculated. The antifungal and antiviral activities of the complexes with Schiff bases derived from anthranilic acid have also been investigated.

4-Aminobenzoic Acid↗
PubMed1986

Toxicity of organic acids for repair-deficient strains of Escherichia coli.

The wild-type strain and four DNA repair-deficient strains (uvrA6, uvrB5, recA56, and polA1) of Escherichia coli K-12 were treated with acetic acid, lactic acid, and p-aminobenzoic acid at pH 3.5 during their stationary phase of growth. All three acids were highly toxic to the polymerase-deficient strain. The greater sensitivity of the strain carrying the polA1 gene than its isogenic pol+ derivatives suggested that damage caused by acidity requires polA+ gene products for repair.

4-Aminobenzoic Acid↗
PubMed1975

Exocrine pancreatic function in protein-deficient patas monkeys studied by means of a test meal and an indirect pancreatic function test.

Exocrine pancreatic secretion was studied in 9 patas monkeys before and during protein depletion, and in 4 of them also during recovery from protein depletion. Pancreatic function was estimated by measuring enzymatic activities in the duodenal contents after a test meal and by determination of urinary excretion of p-aminobenzoic acid (pancreatic function test) after oral ingestion of the chymotrypsin-labile peptide N-benzoyl-L-tyrosyl-p-aminobenzoic acid. The average serum albumin dropped by 34.8% to 2.6 g per 100 ml. Significant decrease of trypsin, lipase, amylase, and chymotrypsin was observed in the duodenal samples during protein deficiency. Urinary excretion of p-aminobenzoic acid was also reduced significantly. The two tests correlated well. In 3 of 4 animals, recovery of pancreatic function was noted after refeeding a full protein diet. Pancreatic atrophy was noted in 2 animals which died. The study shows that exocrine pancreatic secretion can be seriously impaired even at a moderate protein deficiency and may not be reversibly in all instances. Therefore, function tests have to be evaluated with caution when hypoproteinemia, i.e., hypoalbuminemia, is present.

Aminobenzoates↗
PubMed2000

Purification and biochemical properties of an N-hydroxyarylamine O-acetyltransferase from Escherichia coli.

The N-hydroxyarylamine O-acetyltransferase of Escherichia coli has been expressed as a histidine tagged fusion protein and purified using immobilized nickel column chromatography. The molecular mass of the histidine tagged N-hydroxyarylamine O-acetyltransferase was estimated to be 60.0 kDa by gel filtration and 34.0 kDa by SDS-PAGE and DNA sequence, suggesting that the native enzyme exists as homo dimer. The catalytic properties were investigated using o-aminobenzoic acid as a substrate. No difference in acetyltransfer activity was observed between histidine tagged protein and untagged enzyme. Kinetic studies indicated a ping-pong bi bi mechanism of the catalysis. Inhibition by N-ethylmaleimide and salicylic acid was competitive with o-aminobenzoic acid and non-competitive with acetyl-CoA.

Acetyl Coenzyme A↗
PubMed2006

PABA/NO as an anticancer lead: analogue synthesis, structure revision, solution chemistry, reactivity toward glutathione, and in vitro activity.

PABA/NO is a diazeniumdiolate of structure Me(2)NN(O)=NOAr (where Ar is a 5-substituted-2,4-dinitrophenyl ring whose 5-substituent is N-methyl-p-aminobenzoic acid). It has shown activity against human ovarian cancer xenografts in mice rivaling that of cisplatin, but it is poorly soluble and relatively unstable in water. Here we report structure-based optimization efforts resulting in three analogues with improved solubility and stability in aqueous solution. We sought to explain PABA/NO's physicochemical uniqueness among these four compounds, whose aminobenzoic acid precursors differ structurally only in the presence or absence of the N-methyl group and/or the position of the carboxyl moiety (meta or para). Studies revealed that PABA/NO's N-methyl-p-aminobenzoic acid substituent is bound to the dinitrobenzene ring via its carboxyl oxygen while the other three are linked through the aniline nitrogen. This constitutes a revision of the previously published PABA/NO structure. All four analogues reacted with GSH to produce bioactive nitric oxide (NO), but PABA/NO was the most reactive. Consistent with PABA/NO's potent suppression of A2780 human ovarian cancer xenograft growth in mice, it was the most potent of the four in the OVCAR-3 cell line.

4-Aminobenzoic Acid↗
PubMed1976

Observations on the accessibility of acceptor substrates to the active centre of UDP-glucuronosyltransferase in vitro.

The partition coefficients between octanol and pH 7.4 buffer for eleven substrates of UDP-glucuronosyltransferase (EC 2.4.1.17) have been determined. They range between 1.1 and 690 in the order p-aminophenol less than phenol less than (o-aminobenzoic acid = o-aminophenol = p-aminobenzoic acid) less than p-nitrophenol less than 4-methylumbelliferone less than mercaptobenzothiazole less than harmol less than phenolphthalein less than 1-naphthol. The effect of Triton X-100, used as a model membrane pertubant, on the enzyme activity of UDP-glucuronosyltransferase in rat liver homogenates towards these substrates was determined and compared with the partition coefficients. Enzyme activities towards p-aminophenol and phenol were decreased by Triton X-100, the enzyme activities towards other acceptor substrates were enhanced maximally with 0.025% (w/v) Triton. "Native" enzyme activity (except for amino containing compounds) and activation could be related to partition coefficient of the substrate. An increase in lipid solubility resulted in reduced enzyme activity in untreated homogenates and greater activation. These results suggest UDP-glucuronosyltransferase lies behind a partially lipid-impenetrable abrrier and it is suggested that this barrier is broken up by membrane perturbants to permit free access of the more lipid-soluble substrates. In addition, the formation in vitro of a glucuronide from mercaptobenzothiazole was demonstrated.

Aminobenzoates↗
PubMed1979

A method for the simultaneous evaluation of exocrine pancreatic function and intestinal absorptive function in dogs.

Exocrine pancreatic function was evaluated in 13 dogs, using the chymotrypsin-labile peptide N-benzoyl-L-tyrosyl-p-aminobenzoic acid (BT-PABA). This peptide releases p-aminobenzoic acid (PABA) in the presence of pancreatic chymotrypsin. The amount of PABA in blood or urine after BT-PABA administration then served as an index of pancreatic function. Similarly, a xylose absorption test has been described in the literature to evaluate absorptive function of the small intestine. Here, the pentose sugar d(+)xylose was given orally, and blood xylose concentrations were then measured at intervals. Since both tests were performed in nearly the same way, they were combined into a single test. A solution containing BT-PABA (30 mg/ml) and xylose (100 mg/ml) was administered perorally to dogs with and without pancreatic duct ligation. In the unoperated (control) dogs, peak blood concentrations for PABA occurred between 60 and 120 minutes and xylose concentrations were maximal between 30 and 90 minutes. Pancreatic duct ligation reduced PABA concentrations at 90 minutes to one-sixth of the values in control dogs. Xylose absorption, however, was not altered by pancreatic duct ligation. In this way, digestive and absorptive functions were both evaluated, using a single 90-minute test.

4-Aminobenzoic Acid↗
PubMed1990

Phosphate control of pabS gene transcription during candicidin biosynthesis.

The pabS gene of Streptomyces griseus IMRU3570 encodes the enzyme p-aminobenzoic acid synthase, which synthesizes p-aminobenzoic acid (PABA), a precursor of the antibiotic candicidin (Cd). The pabS transcript reached a peak at 12 h of incubation in batch cultures, preceding the formation of PABA synthase and the antibiotic itself. A decay of the pabS transcript was observed with an apparent half-life of 35 min. Inorganic phosphate (Pi; 7.5 mM) reduced the synthesis of the pabS transcript by 90-95%, and consequently the formation of PABA synthase and Cd. Thirty min after addition of 7.5 mM Pi, the cells synthesized only about 15% as much pabS transcript compared to control cultures. However, Pi stimulated two- to threefold total RNA synthesis. The 1.7-kb pabS transcript shown by Northern hybridization was greatly reduced in amount in cells grown in 7.5 mM phosphate. Pi-deregulated mutants, described previously, were impaired in the transcriptional control exerted by Pi. It is concluded that Pi control of PABA synthase and Cd biosynthesis is exerted by repression of formation of the pabS mRNA.

Blotting, Northern↗